travis: postgresql service doesn't seem necessary
travis: postgresql service doesn't seem necessary

mapnik/mapnik,mapnik/mapnik,tomhughes/mapnik,naturalatlas/mapnik,naturalatlas/mapnik,mapnik/mapnik,tomhughes/mapnik,lightmare/mapnik,tomhughes/mapnik,mapnik/mapnik,lightmare/mapnik,tomhughes/mapnik,naturalatlas/mapnik,lightmare/mapnik,naturalatlas/mapnik,lightmare/mapnik